The National Cooperative Inner City Asthma Study is a multicenter, controlled, randomized clinical intervention trial carried out in children with asthma. The study is designed to determine the impact of primary care, clinic-based interventions (asthma counselors, physician education, and control) on symptom days. In New York City, 150 children, 4 to 12 years, from inner city areas, who have moderate to severe asthma with symptoms or on chronic medications during the past year, will be eligible for the investigation. Primary care clinics will be randomized into the 3 intervention groups and the children in these clinics will be followed for 3 years (3 visits/year) after enrollment into the trial. The asthma counselor intervention will be ongoing for 3 years and include modules to reduce environmental (allergens, nitrogen dioxide, environmental tobacco smoke, molds) and psychosocial risks associated with asthma, to increase adherence and to improve asthma management skills. The physician education intervention will consist of 2 formal sessions on asthma management per year for 2 years with feedback on their management practices 3 times per year. An observational study will be done to assess the relation of ambient air pollution to asthma symptoms. A substudy will evaluate the effect of reducing indoor nitrogen dioxide by replacing stoves with pilot lights with ones with auto-ignition lights. Follow-up of symptoms in control and intervention groups will be done by telephone every 2 months. The groups will be compared with respect to symptom days. In addition, comparisons will be made with respect to utilization (unscheduled visits, hospitalizations), adherence, quality of life, physician knowledge and quality of asthma care, asthma-related behavior skills and indoor and outdoor environmental exposures.